High-Tc Susceptometer to Monitor Transfusional Iron Overload

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The proposed research project will continue the application and development of a new method (biomagnetic susceptometry) that measures magnetic fields to determine how much iron is in the liver. The amount of iron in the liver is the best indicator of the amount of iron in the whole body. Measuring the amount of iron in the body is important because either too much (iron overload) or too little iron (iron deficiency) can be harmful. At present, the most reliable way to measure the amount of iron in the liver is to remove a sample of the liver by biopsy, either by surgery or by using a needle which pierces the skin and liver. Iron stored in the liver can be magnetized to a small degree when placed in a magnetic field. In patients with iron overload, the investigators previous studies have shown that magnetic measurements of liver iron in patients with iron overload are quantitatively equivalent to biochemical determinations on tissue obtained by biopsy. In the past the investigators have developed a device to measure the amount of magnetization, which was called a SQUID (Superconducting QUantum Interference Device) susceptometer. This device was validated and in use for over 20 years. The safety, ease, rapidity and comfort of magnetic measurements make frequent, serial studies technically feasible and practically acceptable to patients. The investigators have now developed a new susceptometer, which uses very similar technology to the SQUID, but the investigators believe is more accurate and precise. This study aims to validate this new instrument. The investigators will do prospective, serial studies of the diagnosis and management of patients with iron overload, including thalassemia major (Cooley's anemia), sickle cell disease, aplastic anemia, myelodysplasia, hereditary hemochromatosis, and other disorders. Funding Source - FDA OOPD.

Subjects will first have an ultrasound study to determine the location of the liver and measure the distance from skin surface to the liver. Subjects will then be examined with the high Tc susceptometer to determine the amount of iron in the liver. The entire procedure will usually take one-half hour or less.

The primary study analysis will be a comparison of the results of measurements of the hepatic storage iron concentration by biomagnetic susceptometry with the results of biochemical analysis of the storage iron concentration in liver tissue.

Secondary Outcome Measures :

Serum ferritin concentration [ Time Frame: 2 years ]

A secondary study analysis will be a comparison of the results of measurements of the hepatic storage iron concentration by biomagnetic susceptometry with the results of measurements of the serum ferritin concentration.

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Ages Eligible for Study:

5 Years to 80 Years (Child, Adult, Senior)

Sexes Eligible for Study:

All

Accepts Healthy Volunteers:

Yes

Sampling Method:

Non-Probability Sample

Study Population

Potential participants who are eligible for this study include: (i) patients scheduled for clinically indicated liver transplantation or liver biopsy, (ii) patients with transfusional iron overload followed in adult and pediatric hematology, and (iii) healthy individuals participating as control subjects.

Criteria

Inclusion Criteria:

being an adult male, nonpregnant female or child who is scheduled for liver transplantation, has transfusional iron overload or is healthy with no known disorder affecting body iron stores,

being of sufficient size for the susceptometer (about 15 kg body weight),

being able to lie quietly during the measurement procedure (about 5 to 10 minutes),

being either able to give fully informed consent or, if a minor, with a parent or legal guardian who is able to give fully informed consent for participation of the minor.

Exclusion Criteria:

any form of magnetic contamination or electrical device which cannot be removed for the magnetic measurement procedure, including jewelry, pacemakers, artificial joints, metal staples, indwelling catheters with metallic components, dental braces or other magnetic objects;

obesity, ascites or other conditions in which the liver to surface distance exceeds 25 mm;